Fuel system



Sept. 26, 1961 E. A. JOHNSON 3,001,773

FUEL SYSTEM Filed Oct. 2, 1958 5 Sheets-Sheet 1 FIG.I.

INVENTOR. EL DON A. JOHNSON ATTORNEY Sept. 26, 1961 E. A. JOHNSON 1,

FUEL SYSTEM Filed Oct. 2, 1958 5 Sheets-Sheet z INVENTOR. ELDON A.JOHNSON ATTORNEY p 1961 E. A. JQHNSON 3,001,773

FUEL SYSTEM Filed Oct. 2, 1958 5 Sheets-Sheet 3 e4 1 3; f4; i 1 1/ f l L54;;

I :2 I k I a M i 90 1 i I i l 9/ 92 ee I :1 u z I, n l l 93 37a I I I 730a FIG.5.

' INVENTOR. /3 ELDON A. JOHNSON MQWW , ATTORNEY 1 6 9 1 6 2 m e s 'FUELSYSTEM 5 Sheets sheet 4 Filed 1958 Flc a NTOR. ELDON A. JOH

ATTORNEY Sept. 26, '1961 E. A. JOHNSON FUEL SYSTEM Filed Oct. 2, 1958Sheets-Sheet 5 IIIIHHIIIHIP FIG.9.

INVENTOR. ELDON A. JOHNSON ATTORNEY United States Patent 3,001,773 FUELSYSTEM Eldon A. Johnson, Sunset Hills, Mo., assignor to ACF Industries,Incorporated, New York, N.Y., a corporation of New Jersey Filed Oct. 2,1958, Ser. No. 764,978 15 Claims. (Cl. 261-36) This invention relates tofuel supply systems for internal combustion engines and consistsparticularly in novel means for improving and simplifying the carburetorand relieving the carburetor of the possibility of malfunctioning due toabnormal or subnormal level in the constant level chamber.

There are fuel supply systems for internal combustion engines utilizingcarburetors with constant level chambers of the overflow type and fuelpumps incorporating scavenger devices for evacuating the overflowchambers. Thus, under all normal operating conditions, including engineidling and low speed operation, a constant supply of liquid fuel iscirculated from the pump through the carburetor bowl, thence back to thescavenger pump. In such systems, the scavenger pump is operated by aliquid link from the main pump and during periods of low fuelconsumption, means operate such that the main pump diaphragm stroke isonly sufficient to deliver fuel in quantities slightly in excess of thatbeing consumed by the engine and to cause recirculation through thescavenger pump. In those devices, means referred to apply back pressureupon the main fuel pump in accordance with the delivery pressure of thescavenger pump so as to limit the main pump delivery in accordance withfuel demands of the engine. As long as liquid fuel is being circulatedfrom the spill or overflow chamber through the scavenger pump, thedelivery from the main pump will be restricted. However, when vapor orgaseous material is being drawn through the scavenger pump, therestriction in the main pump fuel delivery line is reduced so that thepumping action of the main pump will be proportionately increased tosatisfy the deficiency in liquid fuel which resulted in the drawing ofvapors into the scavenger pump. However, it has been found in some casesdue to the mounting of the scavenger pump in connection with the fuelpump at some distance below the carburetor, so much time is required fordraining the spill chamber and the lines to the scavenger pump inletcheck valve that the level in the constant level chamber is excessivelylowered with resultant leaning of the fuel mixture supplied to theengine. This results, in turn, in improper functioning of the engineuntil the main fuel pumping action is increased to make up thedeficiency, as above described.

Accordingly, it is the main object of the present invention to rearrangethe scavenger pump in relation to the carburetor spill chamber so thatthe main pump control function of the scavenger pump will be renderedsubstantially more sensitive.

Another object is to mount the scavenger pump directly upon thecarburetor and in immediate proximity to the spill chamber.

Another object is to utilize the valving element whereby thescavenger-pump controls or meters the main pump discharge, as the mainpump discharge check valve, thereby eliminating one valve from theassembly and correspondingly simplifying and reducing the cost thereof.

Another object is to combine the scavenger pump with the main pumpdischarge valving parts. which respond to scavenger pressure conditions.

Another object is to provide means for cutting off the fuel supply linebetween the main fuel pump and the carburetor, when the engine stops, soas to positively prevent forcing of fuel into the carburetor from thepump at such time, as in case of high pressure in the pump and fuel linedue to heat conditions.

Still another object is to provide a fuel supply system incorporating acarburetor fuel bowl of the overflow type and main and scavenger fuelpumps, together with a cut-off valve for the scavenger outlet controlledby a float in the spill or overflow chamber of the carburetor whichsenses stoppage of the powering means of the engine, that is, thedrawing of fuel through the carburetor into the engine, to cut offdelivery from the scavenger pump, thereby increasing the scavenger pumppressure and cutting off the main pump fuel discharge line to thecarburetor.

Still another object is to provide a cutoff valve for the main pumpdischarge line which valve will be opened responsive to the action of acontrol device, such as a manifold suction responsive element,indicating that the powering means of the engine is in operation, andalso responsive to energization of the engines self starter circuit.

These objects and other more detailed objects hereafter' appearing areattained in the present invention in which, in eachform, at least theintake check valve for the scavenger pump is located in immediateproximity to the spill or overflow chamber in the carburetor. In certainof the forms herein disclosed, the entire scavenger pump unit, includingits inlet and outlet check valves, is mounted directly on the carburetorfuel bowl; In another form, the scavenger outlet duct leading to theconstant level chamber may be cut off by a valve actuated by a float inthe spill chamber so that when the fuel level in the spill chamber risesto the stabilized point indicating stoppage of the engine, both thescavenger and main pump discharge lines will be cut off. In still another form, a solenoid-operated cutoff valve controls the main fuel pumpsupply line to the carburetor and is itself controlled by devicesresponding to energization of the ignition and starter circuit andpressure conditions in the intake manifold.

In the accompanying drawings,

FIG. 1 is a schematic side view of an automotive chassis and engineillustrating the components of my novel fuel supply system.

FIG. 2 is a top view of the carburetor of FIGS. 1 and 3 with the bowlcover removed.

FIG. 3 is a somewhat schematic side view, partly in section, of the fuelpump and carburetor assembly.

FIG. 4 is a sectional detail of the carburetor in FIG. 3 in a differentposition.

FIG. 5 is a view similar to FIG. 3 and showing carburetor modifications.

FIG. 6 is another view similar to FIGS. 3 and 5 and showing furthermodifications in the carburetor and fuel pump construcn'on.

FIG. 7 is a wiring diagram applicable to the form in FIG. 6.

FIG. 8 is a detail of the carburetor in FIGS 6 and 7, portions beingsectioned for clearer illustration.

FIG. 9 is a detail vertical transverse section taken on line 9-9 of FIG.8.

In FIG. 1, there is illustrated a chassis 10 having any suitableinternal combustion engine 11 mounted on the forward portion thereof anda fuel supply tank 12 mounted at the rear. The tank is connected bydelivery tube 13 to a mechanical fuel pump 14 mounted at the side ofcrankcase 15 of the engine and operatedby a cam 16 on the enginecamshaft through a pivoted lever 17 FIG. 3). The pump is connected bysupply tubing 18 to the carburetor 19 mounted on manifold 20 by means ofbolting flange 21 in the customary manner. An engine exhaust manifold isshown at 22.

The carburetor (FIGS 2 and 3) has a pair of downdraft mixture conduits25, each including an inner venturi tube 26 into which discharges a mainsupply nozzle 27. At the side of the carburetor is a fuel supply bowl,generally indicated at 28, having parallel partitions or weirs 29,forming a central, constant level chamber or bowl 30 and side spill oroverflow chambers 31. Within chamber 30, is a cylinder 32 for mountingan accelerating pump and a second cylinder 33 for receiving a suctionstep-up device, as shown for instance, in the Patent 2,635,625 toMoseley et al. Pivotally mounted in the merged upper part 34 of themixture conduit structure is a butterfly choke valve 35 for whichsuitable control mechanism (not shown) is provided, A fast idle cam 36is carried at the end of choke shaft 37 for cooperation with an abutmentscrew 38 on pivoted lever 39 connected to the throttle valve 40 by alink 41.

At the bottom of the constant level bowl 30 are a pair elements may becontrolled by suitably-operated metering rods or valves, as shown in theabove-mentioned patent to Moseley et al. Bowl cover 44, formed integralwith air inlet 34, is provided with a suitable vent opening 45, whichmay be connected to a balance tube opening into the air inlet, or to theatmosphere outside the air inlet, as desired. Fuel inlet fitting 46 ismounted in the side wall of the bowl structure and is connected by meansof tube 18 to main discharge fitting 47 of fuel pump 14. Bowl fitting 46opens through a cap 48 secured by bolts 49 to scavenger pump body 50which is formed as an integral enlargement on the bowl end wall. Thediaphragm 51 clamped between cap 48 and body 50, divides cavity 52between the cap and body into a pulsing chamber 53 and a pumping chamber54. Ports 55 in the bottoms of spill chambers 31 connect with pumpchamber 54 by means of a cross passage 56 and an inlet duct 57 receivinginlet check valve 58. An outlet duct 59 leads from pump chamber 54 intoconstant level bowl 30 and accommodates a discharge check valve 60.Valve seat 61 forms a calibrated restriction in the scavenger pumpoutlet passage, to be referred to hereafter.

Main fuel inlet fitting 46 communicates with pulsing chamber 53 andthence, through a passage 62, with constant level bowl 30. Passage 62terminates within pulsing chamber 53 in a nipple 63 forming a valveseat. Cooperating with this seat is a disc valve element 64 centrallysecured to diaphragm 51 by means of the upset head 65 of rivetprojecting from a washer 66. A coiled spring 67 compressed betweenwasher 66 and recess 68 in cavity 52 normally urges valve 64 toward seat63 for closing main pump delivery passage 18, 46, 53, 63 and 62.

Fuel pump 14 consists of body members 70 and 71 clamping therebetween amain pumping diaphragm 72. An actuating stem 73 is centrally secured todiaphragm 72 by means of clamping washers 74 and 75, the outerperipheries of which are shaped to constantly maintain the intermediatefree flexing portion of diaphragm 72 in a fold or bight directed intomain pumping chamber 76. Fuel delivery tube 13 leading from tank 12connects with main pump inlet fitting 77 which opens into pumpingchamber 76 through inlet passage 78 formed in adepression in casing 71.A spider 79 in this depression has an annular series of inlet ports 80controlled by a flexible disc inlet check valve 81 held in position by amushroom valve retainer 82. The under wall of the valve retainer isconical as shown to permit upward flexing of the outward portion ofvalve disc 81. No outlet check valve is provided in the main pump, valve64 in the scavenger device serving as an outlet check, as will bedescribed hereafter. Diaphragm 72 is constantly urged downwardly, in thepumping direction, by a coiled compression spring 83.

During normal operation of the engine, tates to cause rocking of lever17 and intermittent lifting of stem 73 and main pumping diaphragm 72 fordrawing fuel into pumping chamber 76. The intervening discharge strokesof the pump are produced by spring 83 so that, theoretically, thedischarge pressure of the pump is limited by the characteristics ofspring 83.

During each upward, charging stroke of main pumping diaphragm 72, thepressure in pulsing chamber 53 is reduced and scavenger diaphragm 51 ismoved to the right as seen in FIG. 3, so as to draw fluid from spillchambers 31 into scavenger pumping chamber 54. It will be seen thatscavenger diaphragm has considerable slack so as to form a relativelylarge loop or bight 51a in the free flexing portion thereof.Furthermore, chambers 53 and 54 are shaped to permit substantiallygreater flexing of diaphragm bight portions 51a than is necessary forseating valve 64 during the charging stroke of diaphragm 51.Consequently, early in this charging stroke, disc valve 64 seats uponnipple 63, thus sealing discharge tube 18 and, thereby, functioning as amain pump discharge check valve. As stated, diaphragm bight or loop 51acan continue its pumping movement so as to draw a substantial quantityof fluid into scavenger pumping chamber 54.

As the stroke of main pump diaphragm 72 reverses, inlet check 81, ofcourse, closes and fluid in main pumping chamber 76 is forced outwardlythrough tubing 18 into pulsing chamber 53 where it is applied toscavenger pump diaphragm 51 so as to force the diaphragm to the left asviewed in FIG. 3, first flexing loop 51a in the opposite direction, thenforcing disc valve 64 from its seat. The pumped fuel then passes throughpassage 62 into constant level bowl 30.

In time, after initial starting of the engine, liquid fuel will fill theconstant level bowl and overflow into spill chambers 31. Thereafter,liquid fuel will be drawn into scavenger pumping chamber 54 upon eachintake stroke and returned past outlet check 60 into the constant levelbowl during each discharge stroke of the scavenger diaphragm. Due torestriction 61 in the scavenger pump outlet, there will be a resistanceimposed on the discharge of fluid from the scavenger pump chamber 54,and this resistance is so calibrated as to limit the movement ofdiaphragm 51a to a flexing action of an amount such as indicated in thedotted line position in FIG. 3. The flexing action is in timed relationto the main pump, and the output pressure of both pumps is proportional.Ordinarily, this amount of movement of the diaphragm is all that isrequired to maintain a continuous circulation of fluid from thescavenger chamber 54 into the overflow chamber 30. The movement of thediaphragm 51a may be insuflicient, however, to compress spring 67 andmove valve 64 from its seat, so that, consequently, there is very littlefuel delivered from the main pump 14 through the connection 18 to thepassage 62 and fuel bowl 30.

This operation of the scavenger pump will continue so long as there issutficient fuel being supplied to the outlet passages 55. However, whenone or the other of these passages becomes uncovered, or for any otherreason air or vapors are sucked into the pumping chamber 54, the flexingaction of the scavenging pump diaphragm will increase as shown in FIG.4. Air or vapors, as the case may be, have a much lower viscosity thanfuel, and metering restriction 61 will become less of a resistance tothe discharge; consequently, the degree of flexing of the diaphragm 51aunder the effect of pump pressure will increase, increasing the strokeof the scavenger pump far enough to lift the valve 64 fully from itsseat, as in FIG. 4, whereupon a full flow of fuel is delivered from thechamber 53 and passage 62 into the chamber 30 to supplement thedecreased delivery into this same chamber by the scavenger pump, whichnow is discharging a smaller amount of liquid, in spite of its increasein stroke. This condition in which the scavenger pump stroke increases,lif the va ve 64., will n i i e. until. sutfic ent el. has be n iv ed taga n l he pa ag 56 1 and over.

the overflow outlets 55, and fill chamber 54 with solid fuel. 7

It should be understood that, in the operation of the device, both themain pump 14 and the scavenger pump operated thereby may be deliveringinto the chamber 30 simultaneously, although the amount of delivery fromthe scavenger pump, under these circumstances, is below that required tomeet engine demand.

Thus, during normal operation, the main pump 14 will continuouslyoperate the scavenger pump, and the scavenger pump, in turn, willoperate to circulate the fuel from the overflow chambers to the constantlevel chamber 30. The stroke of the scavenger pump, however, will vary,depending upon the amount of solid fuel being circulated, thus liftingthe valve 64 in varying degree and intermittently to supplement theamount of fuel delivered from the scavenger pump by fuel delivereddirectly from the main pump. At no time, however, will there beinsufiicient fuel delivered from the pumps to maintain the chamber 30full of fuel, because lines 18, chamber 53, and passage 62 are alwaysfull of fuel. Preferably, the restriction 61 is calibrated to have asmall flow capacity at scavenger pump pressure.

The relationship between the elements in this comb-ination is notparticularly critical, but it requires that the main pump 14 should havea capacity much greater than the scavenger pump. This is so because itis desirable, when the engine stops, to have the scavenger pump valve 64seal the discharge from the main pump so that there will be no fueldelivery from the main pump directly into the overflow chamber 30.

It will be realized that this will occur naturally when the engine isshut off with the combination of elements disclosed. When the engineignition is cut off to stop the engine, the engine will rotate severaltimes due to inertia of the parts, and the fuel drawn into the engine atthat time will be little in comparison with the capacity for delivery ofthe main pump 14. As a consequence, there will be enough fuel deliveredeither from the scavenger pump or from the main pump so as to coveroutlets 55 and fill the pumping chamber 54 with solid fuel, and when thechamber 54- is full of solid fuel, the resistance of the diaphragm 51 tomovement is increased due to the small size of restriction 61, and thisincrease in resistance, plus the pressure of the spring 67, is usuallysuflicient to prevent the valve 64 from lifting and allowing fuel toburp over into the fuel bowl of the carburetor from the main pumpcircuit when the engine stops and until pressure in the chamber 54bleeds down. The valve 64 and diaphragm 51 are therefore temporarilymaintained in the position shown in FIG. 3, rather than in the conditionshown in FIG. 4, in which the discharge passage from the main pump isopen.

It should be especially noted that inlet check valve 58 of the scavengerpump is mounted in immediate proximity to spill chambers 31. Thus, aminimum of time will elapse between the ceasing of pumping of normalliquid fuel by the main pump, and the sensing of this fact by thescavenger pump so as to increase the main pump stroke. Accordingly, thespill chambers should be only large enough to maintain the scavengerinlet submerged under normal operating conditions while quickly exposingthis inlet to gases when the liquid delivery of the main pump isdeficient.

The operation of the modification in FIG. is very similar to that abovedescribed with respect to FIGS. 3 and 4. In this modification, thedischarge resistance imposed upon the scavenger pump is primarilydetermined by the float 93 and its valve 91. The surface of the valve 91is quite large, and the discharge metering orifice 90 provides a valvesurface which extends over considerable area of the flat float valve 91,so that during operation of the scavenger pump the discharge pressurethereof will tend to force the float off of its seat, and fuel will besupplied from the scavenger pump into the fuel chamber 30a against theresistance int? posed. by the float valve 91 and the float 93. Themaximum resistance imposed by the float 93 and the valve 91 can beeasily calibrated, since the maximum fuel level is known, and will neverexceed the depth of the fuel chamber 30a. Thus, the amount ofdisplacement and the maximum force imposed by the float 93 on the valve91 can be easily calibrated. This closing force'is so selected thatsuflicient restriction is provided to cause the scavenger pump diaphragm51b to flex in the same manner as disclosed in FIG. 3, so the valve 64awill be maintained on the seat 63a as long as there is a substantialfuel supply within the scavenger bowl 31a and the pump chamber 54a issubstantially full of fuel. However, when the pumping chamber 54abecomes low on fuel and float valve 91 opens, the flexing of thediaphraghm 51b increases, and the same operation occurs as illustratedin the modification shown in FIG. 4. Valve 64a is moved from its seat,and fuel is immediately available from the main pump 14a and deliveredthrough the passage 62a into the float chamber 30a. Thus, fuel will bedelivered from both the main pump 14a and the scavenger pump into thefloat chamber 30a, so that the level herein will always be maintained atmaxi-mum. When the ignition of he engine is turned off, the engine w'llrotate several cycles, and the fuel consumption at this time is very lowas compared with the maximum delivery of the main pump 14a, whichinsures that the chamber 30a will be full of fuel so that the float 93will be in the raised position, closing the valve 91. The residualpressure in the chamber 54a, plus spring pressure, will then besuflicient to prevent intermittent surges or burping' of fuel into thefloat bowl from the main pump through the circuit to the float chamber30a after the engine stops and, unlike the first modification, thiscondition will continue until the engine is restarted.

In the form of FIG. 6, scavenger diaphragm is clamped to main pump body101 by means of lower casing or cap structure 102. A plurality of ampleports 103 are formed in body 101 immediately above diaphragm 100 tohydraulically connect main pumping chamber 104 with pulsing chamber 99between diaphragm 100 and casing 101. The remaining portions of the mainfuel pump are generally similar to corresponding parts in FIGS. 3 and 5,including inlet check 81a, main pumping diaphragm 72a, and inlet andoutlet fittings 77a annd 47a.

A single fitting 105 formed in the bottom wall of scavenger pumpingchamber 106 is connected by a tube 107 and a fitting 108 to cap 109,which is secured to a thickened body part 110, formed on the side offuel bowl structure 28a. Ftting 108 communicates through a passage 111in cap 109, restricted orifice 112, and passages 113 and 114,respectively, in the cap and thickened bowl wallportion, with centralconstant level chamber 3%, corresponding with chamber 30 in FIG. 3.Fitting 108 also communicates by means of passages 115 in the cap and116 and 117 in the bowl structure with ports 55a at the bottoms of spillchambers 31b. An inlet check valve 118 is received in each port 55a andan outlet check valve 119 is provided in passage 11,1. Passage 11-1 isconnected by a short duct 161 to pressure chamber 162 at the right sideof diaphragm 120, to be described.

Secured between cap 109 and thickened bowl wall portion 110 is thediaphragm 120 carrying a central disc valve 121 for seating on thenipple 122 formed at the end of a passage 123 with which main .fuelinlet fitting 46b communicates. Diaphragm 120 and valve 121 are normallyurged leftwardly, toward a restricting position with respect to seating122, by a coiled spring 124. 1

A solenoid 126, having control wiring 1-27 and 128, is mounted on cap109 and has an armature 129 on opposite sides of brass cover plate 130on cavity 131,

formed in cap 109. At the inner end of the armature is a pointed pin 132forming a valve for cooperating with previously-mentioned orificerestriction 112. A coiled spring 133 compressed between cover 139 and acollar 134 on the armature constantly urges valve 132 leftwardly, ortowards its seating position.

As shown in FIG. 7, solenoid control wire 128 is grounded. Control wire127 extends to a teminal 138 on a housing 139 secured to carburetor airinlet horn 140. The other terminal 141 of this casing is connected by awire 142 to ignition switch 143, thence by wire 144 to battery 145. AWire 146 leads to the usual ignition circuit (not shown). As will beWell understood, the ignition-battery circuit will include the usualgenerator which, however, is not here represented.

Casing 139, as shown in detail in FIG. 9, encloses a flexible diaphragm147 constantly urged rlghtwardly by a coiled spring 148. Centrallysecured to the diaphragm in a pin 149 which carries a switch blade 150for bridging contacts 151 and 152 in electrical connection withterminals 138 and 141 previously mentioned. A push pin 153 is slidablyreceived in the cover portion of casing 139 and is normally urgedoutwardly by spring 148 acting through pin 149. A camming arm 154,formed on a lever 155 pivoted at 156 to the bowl cover, is connected bya link 157 to throttle-operating arm 158. The arm is provided with aperforation 159 for connection by suitable linkage (not shown) to theaccelerator pedal in the drivers compartment. Throttle 40a is mounted ona shaft 160 which is journalled in the side walls of the carburetor. Oneend of shaft 160 extends into a chamber 161 formed in a boss 162 onthrottle body 163. Slidable in a side wall of boss 162 is a plunger 164having a dished lower extremity 165 which cooperates with a ball 166received in chamber 161. The end of the throttle shaft is segmented asat 160a for actuating ball 166 under certain conditions. Projecting fromplunger 164 is a switch blade carrying member 167 of insulating materialwhich is constantly urged downwardly by a coil spring 168. Intakemanifold suction, posterior to throttle 40a is transmitted to chamber161 through a port 169. This type of throttleoperated starter switchstructure is more fully described in Coffee Patent No. Re. 22,030.

Briefly, when there is no suction in the intake manifold, as when theengine powering means is not in operation, ball 166 will be droppedbetween segmented face 160a on the end of throttle shaft 160 and dishedend 165 on plunger 164. When the throttle valve is opened to its properstarting position, switch carrier 167 will be elevated sufficiently toclose the switch contacts (not shown) and energize the automatic startercircuit wires 170 and 170a. When the engine starts to run under its ownpower, the suction in the intake manifold will in crease sharply sothat, when the throttle is returned to its idling position, as Willnormally occur, ball 166 is released and drawn upwardly to renderthrottle shaft 160 inoperative thereafter to re-close the starter switchas long as the engine is running.

Casing 139, previously mentioned, is connected by a passage 171 to theengine intake manifold so that manifold suction conditions are appliedto the left-hand side of diaphragm 147. The right-hand side of thediaphragm will be exposed to atmospheric conditions through a suitablevent in the cap portion of casing 139.

The structure of FIGS. 6-9 operates as follows: When ignition switch 143is closed and the throttle valve is opened for starting the engine,switch blade 150 will be closed, through link 157, lever elements 155and 154, and push pin 153, to energize solenoid 126. This causeswithdrawal of valve 132 from its seat element 112 to permit a supply offuel to flow to the carburetor and engine for starting. After the enginestarts to run under its own power, the intake manifold suction willbuild up sufiicientlyto hold diaphragm 147 in its leftward positionmaintaining switch 150 closed. The switch cannot thereafter open, aslong as the engine is running, even under the most adverse enginesuction conditions which would be accompanied by substantial opening ofthe throttle. This, in turn, acts through lever elements 154 and 155 tomechanically hold switch 150 closed and solenoid 126 is energized tohold open the valve 132.

During pumping action of main pump diaphragm 72a scavenger pumpdiaphragm is caused to reciprocate, alternately drawing fluid past inletcheck valves 118 and forcing this fluid through outlet check valve 119and orifice restriction 112 and passages 113 and 114 into constant levelbowl 30b. When substantial quantities of vapor or gaseous matter arebeing drawn past inlet checks 118 and forced past check 119 and throughpassage 161 into pressure chamber 162, there is insurlicient backpressure against diaphragm to hold valve 121 in a restricting positionagainst the main pump discharge pressure so that valve 121 opens and themain pump diaphragm is permitted increased pumping action. However, whenliquid is being pumped through passages 116, 111, and 161, the resultantback pressure on diaphragm 120 will cause restriction of the main pumpdischarge passaging 4611, 123, and 162. As previously explained inconnection with FIGS. 3 and 5, during normal operation, valve 121 willact as a metering valve to adjust the pumping action of the main pump inproportion to the requirements of the engine. Also, as previouslyexplained, disc valve 121 will be drawn against seating 122 during eachintake stroke of the main pumping diaphragm so that this valve functionsin lieu of the usual discharge check valve heretofore mounted in thepump body.

It should be understood that in this modification, the scavenger pumpand the diaphragm operated valve are two distinct elements, rather thancombined, as heretofore in the previous modifications, and that thevalve 121 is normally held closed due to the fact that, although theressure in lines 18 and 107 is substantially the same, the area uponwhich this pressure acts on the diaphragm 120 and the valve 121 is soout of proportion that the valve 121 will slightly open onlyintermittently on each pump stroke so long as there is a solid column offuel held under pressure in the chamber 162 by the small restriction112. This, in turn, depends upon Whether or not there is sufficient fuelin the overflow chamber 315 to feed the scavenger pump 106, which drawsthe fuel in through the intake valve 118 and exhausts the fuel throughthe outlet 119, filling the chamber 162 and producing a head of fuelpressure against the diaphragm 2i} proportional to the resistance of themetering restriction 112. This metering restriction is so selected as tohave a capacity which is preferably smaller than the maximum rate offuel consumption by the engine.

Any time that bubbles of air or vapors begin to accumulate within thechamber 162 or on the discharge side of the check 119, the force on thediaphragm 120 diminishes very rapidly, due to the fact that the pressuredrops in the chamber 162. As the closing force on the diaphragm 120diminishes, it will eventually become insufficient to hold the valve 121closed against the full head of pump pressure from the main pump throughthe line 18, and fuel will then pass the valve 121 and flow through thepassages 162 and 114 to the fuel bowl. A supplemental amount of fuel issimultaneously delivered through the passages 111 and 113 from scavengerpump action.

When the ignition is turned off, solenoid 126 is completelyde-energized, and spring 133 closes metering restriction 112. Theconsumption of fuel of the engine will be low, and, it will rotateseveral times due to the inertia of the parts. Since the fuelconsumption is low and the pump capacity is relatively large, there willbe sufficient fuel delivered to fill overflow chamber 31!) so that thebooster pump will be producing a full head of fuel to close the valve121. If new heat produces an excessively high pressure in any one of thelines 107 or 118, the valve 121 will remain closed, preventing fuelburping through the line 18 and into the fuel bowl.

Accordingly, means have been provided for accomplishing all of theobjects set forth heretofore. Of course, the various carburetor andengine control features may be modified in various respects as willoccur to those skilled in the art and exclusive use of all modificationsas come within the scope of the appended claims is contemplated.

I claim:

1. A fuel supply system for an internal combustion engine comprising acarburetor having bowl structure forming a constant level chamber of theoverflow type and a spill chamber for receiving overflow therefrom, acavity in a wall of said bowl structure, a flexible diaphragm traversingsaid cavity and forming, respectively, a pulsing chamber and a scavengerpumping chamber on opposite sides thereof, inlet and outlet duets withcheck valves leading from said pumping chamber to said spill andconstant level chambers, respectively, a main fuel pump having adischarge passage leading to said pulsing chamber and thence to saidconstant level chamber, there being a valve seat on a portion of saiddischarge passage opening into said pulsing chamber and a valve elementcarried by said diaphragm for cooperating with said seat to variablyrestrict said discharge passageresponsive to varying pressuredifferential in said pulsing and pumping chambers.

2. A fuel supply system as described in claim 1 in which said diaphragmhas suficient slack to flex in rhythm with the pumping action of saidmain pump for causing pumping through said ducts even when said valveelement is in a restricting position with respect to said seat.

3. A fuel supply system as described in claim 2 in which said valveelement is designed to seat during each intake stroke of said main pumpso as to function as an outlet check valve therefor.

4. A fuel supply system for an internal combustion engine, said systemcomprising a carburetor having a constant level fuel bowl of theoverflow type and a spill bowl for receiving overflow fuel from saidfuel bowl,

- means forming a cavity within said carburetor and an inlet passage tosaid cavity, a flexible diaphragm sealed across said cavity and formingtwo chambers, a check valve element carried by said diaphragm, an outletpassage from one of said cavity chambers to said fuel bowl, said outletpassage having a valve seat surface within said one cavity chamber, aspring biasing said check valve element against said valve seat surfaceto close said outlet passage, an inlet duct connecting said spill bowlwith the other one of said two chambers, an inlet valve structure withinsaid inlet duct, an outlet duct means connecting said other chamber withsaid fuel bowl, an outlet valve structure within said outlet duct, amain fuel pump having an outlet therefrom, conduit means connecting saidpump outlet with one end of said carburetor inlet passage, the other endof said carburetor inlet passage opening into said one cavity chamberwhereby pulsations of fuel pumped through said conduit means will exertpressure pulses on said diaphragm.

5. A' fuel supply system for an internal combustion engine, said systemcomprising a carburetor having a constant level fuel bowl of theoverflow type and a spill bowl for receiving overflow fuel from saidfuel bowl, means forming a cavity within said carburetor and an inletpassage to said cavity, a flexible diaphragm sealed across said cavityand forming a pulsating chamber and a scavenging chamber, a check valveelement carried by said diaphragm, an outlet passage from said pulsatingchamber to said fuel bowl, said outlet passage having a valve seatsurface within said pulsating chamber, a spring biasing said check valveelement in opposition to fuel pressure in said pulsating chamber andagainst said valve seat surface toclose said outlet passage, an inletduct connecting said spill bowl with said scavenging chamber, an inletvalve structure within said inlet duct, an outlet duct means connectingsaid scavenging chamber with said fuel bowl, an outlet valve structurewithin said outlet duct, a main fuel pump having an outlet therefrom,conduit means connecting said pump outlet with one end of saidcarburetor inlet passage, the other end of said carburetor inlet passageopening into said pulsating chamber whereby pulsations of fuel pumpedthrough said conduit means will exert pressure pulses on said diaphragm.

6. A fuel supply system for an internal combustion engine, said systemcomprising a carburetor having a constant level fuel bowl of theoverflow type and a spill bowl for receiving overflow fuel from saidfuel bowl, a main fuel pump having a pumping chamber and an outlettherefrom, said carburetor including a pair of chambers, fuel passagemeans connecting one of said chambers to said main fuel pump outlet andsaid fuel bowl, said fuel passage means including a valve seat surfaceand a check valve element within said one chamber, means biasing saidcheck valve element against said valve seat surface to close said fuelpassage, a scavenging pump including fuel duct structure connecting saidspill bowl and said fuel bowl with the other one of said chambers, aninlet valve within said duct structure between said spill bowl and saidother chamber, means forming a restricted orifice within said ductstructure between said other chamber and said fuel bowl, a diaphragmexposed to fuel in said pumping chamber and to fuel in said ductstructure for exerting pumping pressures to the fuel in said ductstructure.

7. A fuel supply system for an internal combustion engine, said systemcomprising a carburetor having a constant level fuel bowl of theoverflow type and a spill bowl for receiving overflow fuel from saidfuel bowl, a main fuel pump having a pumping chamber and an outlettherefrom, said carburetor including a pair of chambers, fuel passage ofsaid chambers to said main fuel pump outlet and said fuel bowl, saidfuel passage means including a valve seat surface ahd a check valveelement within said one chamber, means biasing said check valve elementagainst said valve seat surface to close said fuel passsage, ascavenging pump means including fuel duct structure connecting saidspill bowl and said fuel bowl with the other one of said chambers, aninlet valve within said duct structure between said spill bowl and saidother chamber, means forming a restricted orifice within said ductstructure between said other chamber and said fuel bowl, a diaphragmexposed to fuel in said pumping chamber and to fuel in said ductstructure for exerting pumping pressures to the fuel in said ductstructure, closure means for said restricted orifice including a valveand a valve seat, and structure for biasing said valve against saidvalve seat.

8. A fuel supply system for an internal combustion engine, said systemcomprising a carburetor having a constant level fuel bowl of theoverflow type and a spill bowl for receiving overflow fuel from saidfuel bowl, a main fuel pump having a pumping chamber and an outlettherefrom, said carburetor including a pair of chambers, fuel passagemeans connecting one of said chambers to said main fuel pump outlet andsaid fuel bowl, said fuel passage means including a valve seat surfaceand a check valve element within said one chamber, means biasing saidcheck valve element against said valve seat surface to close said fuelpassage, a scavenging ump means including fuel duct structure connectingsaid spill bowl and said fuel bowl with the other one of said chambers,an inlet valve within said duct structure between said spill bowl andsaid other chamber, means forming a restricted orifice within said ductstructure between said other chamber and said fuel bowl, a

diaphragm exposed to fuel in said pumping chamber and to fuel in saidduct structure for exerting pumping pressures to the fuel in said ductstructure, and closure means for said restricted orifice including avalve, a valve seat and structure for biasing said valve against saidvalve seat, said biasing structure comprising a float device within saidfuel bowl.

9. A fuel supply system for an internal combustion engine, said systemcomprising a carburetor having a constant level fuel bowl of theover-flow type and a spill bowl for receiving overflow fuel from saidfuel bowl, a main fuel pump having a pumping chamber and an outlettherefrom, said carburetor including a pair of chambers, fuel passagemeans connecting one of said chambers to said main fuel pump outlet andsaid fuel bowl, said fuel passage means including a valve seat surfaceand a check valve element within said one chamber, means biasing saidcheck valve element against said valve seat surface to close said fuelpassage, 21 scavenging pump means including fuel duct structureconnecting said spill bowl and said fuel bowl with the other one of saidchambers, an inlet valve within said duct structure between said spillbowl and said other chamber, means forming a restricted orifice withinsaid duct structure between said other chamber and said fuel bowl, adiaphragm exposed to fuel in said pumping chamber and to fuel in saidduct structure for exerting pumping pressures to the fuel in said ductstructure, said orifice means including a valve seat, a valve, andstructure to bias said valve against said valve seat, and meansincluding a solenoid to open said valve against the action of saidbiasing structure.

10. A fuel supply system for an internal combustion engine, said systemcomprising a carburetor having a constant level fuel bowl of theoverflow type and a spill bowl for receiving overflow fuel from saidfuel bowl, means forming a mixture conduit extending through saidcarburetor, a throttle valve movably mounted within said mixtureconduit, a main fuel pump having a pumping chamber and an outlettherefrom, said carburetor including a pair of chambers, fuel passagemeans connecting one of said chambers to said main fuel pump outlet andsaid fuel bowl, said fuel passage means including a valve seat surfaceand a check valve element within said one chamber, means biasing saidcheck valve element against said valve seat surface to close said fuelpassage, a scavenging pump means including fuel duct structureconnecting said spill bowl and said fuel bowl with the other one of saidchambers, an inlet valve within said duct structure between said spillbowl and said other chamber, means forming a restricted orifice withinsaid duct structure between said other chamber and said fuel bowl, adiaphragm exposed to fuel in said pumping chamber and to fuel in saidduct structure for exerting pumping pressures to the fuel in said ductstructure, said orifice means including a valve seat, a valve, andstructure to bias said valve against said valve seat, and meansincluding a solenoid to open said valve against the action of saidbiasing structure, said last means comprising an electrical circuitincluding said solenoid and a switch operatively connected to saidthrottle.

11. A fuel supply system for an internal combustion engine, said systemcomprising a carburetor having a constant level fuel bowl of theoverflow type and a spill bowl for receiving overflow fuel from saidfuel bowl, means forming a mixture conduit extending through saidcarburetor, a throttle valve operatively mounted within said mixtureconduit, a main fuel pump having a pumping chamber and an outlettherefrom, said carburetor including a pair of chambers, fuel passagemeans connecting one of said chambers to said main fuel pump outlet andsaid fuel bowl, said fuel passage means including a valve seat surfaceand a check valve element within said one chamber, means biasing saidcheck valve element against said valve seat surface to close said fuelpassage, a scavenging pump means including fuel duct structureconnecting said spill bowl and said fuel bowl with the other one of saidchambers, an inlet valve within said duct structure between said spillbowl and said other chamber, means forming a restricted orifice withinsaid duct structure between said other chamber and said fuel bowl, adiaphragm exposed to fuel in said pumping chamber and to fuel in saidduct structure for exerting pumping pressures to the fuel in said ductstructure, a valve device in said duct structure for controlling fuelflow through said orifice, an electrical circuit including a solenoidand a switch for closing said circuit to open said valve device, airmotor means operatively connected to said switch, and means forming apassage from said air motor to a point in said mixture conduitdownstream of said throttle valve.

12. A carburetor comprising a constant level fuel bowl of the overflowtype and a spill bowl for receiving overflow fuel from said fuel bowl,means forming a cavity within said carburetor and an inlet passage tosaid cavity, a flexible diaphragm sealed across said cavity and formingtwo chambers, a check valve element carried by said diaphragm, meansforming a fuel passage in said carburetor extending into one of saidcavity chambers and to said fuel bowl, said fuel passage having a valveseat surface within said one cavity chamber, a spring biasing said checkvalve element against said valve seat surface to block said fuelpassage, fuel duct means connecting said spill bowl and said fuel bowlwith the other one of said two chambers, an inlet valve structure insaid fuel duct means between said spill bowl and said other chamber,means forming a restricted orifice within said fuel duct means betweensaid other chamber and in said fuel bowl, and means to control the flowof fuel through said restricted orifice, said carburetor inlet passageextending from an inlet thereto to said one cavity chamber, wherebypulsations of fuel pumped into said inlet passage will exert pressurepulses on said diaphragm.

bers and to said fuel bowl, said fuel passage having a valve seatsurface within said one cavity chamber, a spring biasing said checkvalve element against said valve seat surface to block said fuelpassage, fuel duct means connecting said spill bowl and said fuel bowlwith the other one of said two chambers, an inlet valve structure withinsaid fuel duct means between said spill bowl and said other chamber,means, forming a restricted orifice within said fuel duct means betweensaid other chamber and said fuel bowl, and means to control the flow offuel through said restricted orifice, the inlet end of said carburetorinlet passage being adapted to be connected to a fuel pump, the otherend of said carburetor inlet passage opening into said one cavitychamber whereby pulsations of fuel pumped through said inlet passagewill exert pressure pulses on said diaphragm, said orifice control meansincluding a float in said fuel bowl to bias said orifice control meansin an orifice closing direction.

14. A carburetor comprising a constant level fuel bowl of the overflowtype and a spill bowl for receiving overflow fuel from said fuel bowl,means forming a cavity within said carburetor and an inlet passage tosaid cavity, a flexible diaphragm sealed across said cavity and formingtwo chambers, a check valve element carried by said diaphragm, meansforming a fuel passage in said carburetor extending into one of saidcavity chambers and to said fuel bowl, said fuel passage having a valveseat surface within said one cavity chamber, a spring biasing said checkvalve element against said valve seat surface to block said fuelpassage, fuel duct means conmeeting said spill bowl and said fuel bowlwith the other one of said two chambers, an inlet valve structure insaid fuel duct means between said spill bowl and said other chamber,means forming a restricted orifice within said fuel duct means betweensaid other chamber and said fuel bowl, and means to control the flow offuel through said restricted onifice, the inlet end of said carburetorinlet passage being adapted to be connected to a fuel pump, the otherend of said carburetor inlet passage opening into said one cavitychamber whereby pulsations of fuel pumped through said inlet passagewill exert pressure pulses on said diaphragm, said orifice control meansincluding a closure valve, a spring operatively connected to saidclosure valve to bias said closure valve into an orifice closingposition and a solenoid means mounted on said carburetor to open saidclosure valve against the bias of said spring.

15. A carburetor comprising a constant level fuel bowl of the overflowtype and a spill bowl for receiving overflow fuel from said fuel bowl,means forming a cavity within said carburetor and an inlet passage tosaid cavity, a flexible diaphragm sealed across said cavity and formingtwo chambers, a check valve element carried by said diaphragm, meansforming a fuel passage in said carburetor extending into one of saidcavity chambers and to said fuel bowl, said fuel passage having a valveseat surface within said one cavity chamber, a spring biasing said checkvalve element against said valve seat surface 14 to block said fuelpassage, said spill bowl and said fuel bowl with the other one of saidtwo chambers, an inlet valve structure in said fuel duct means betweensaid her, means forming a restricted orifice within said fuel duct meansbetween said other chamber and in said fuel bowl, and means to controlthe flow of fuel through said restricted orifice, the inlet end of saidcarburetor inlet passage being adapted to be connected to a fuel pump,the other end of said carburetor inlet passage opening into said onecavity chamber whereby pulsations of fuel pumped through said inletpassage will exert pressure pulses on said diaphragm, said orificecontrol means including a ball valve in said duct structure and a springbiasing said ball valve into said orifice.

References Cited in the file of this patent UNITED STATES PATENT 5FOREIGN PATENTS 348,108 Germany Ian. 30, 1922 fuel duct means connectingI spill bowl and said other cham

